Tap switch



Oct. 20, 1931. A. HALLER ET AL 1,828,496

TAP SWITCH Filed May 10, 1929 Invenzars Arnold Heller Sigurd Rump A ttbrney Patented Oct. 20, 1 931 UNITED f sfrA'r-ss PATENT OFFICE ARNOLD HALLER, 0F BADEN, SIG'UR'D HUME, OF ZURICH, SWITZERLAND, ASSIGN- ORS T0 AKTIENGESEILSCHAFT BRO'W'N BO'V'EBI & 0115., OJ! BADEN, SWITZERLAND, A JOINT-STOCK COMPANY 01' 1 TAP SWITCH Application and Kay in, 192s, semi no.

This invention relates to improvements .in electric switches and, more particularly, to step switches such as are used for changing the ratio of transformers.

When it becomes. necessary to change the ratio of a transformer, it is desirable that such change be made while the apparatus is under load to avoid the loss of time andefiort required for disconnecting and reconnecting the apparatus. Suchchange may be made in :1. continuous or in a step-by-step manner. "ll hen the step-by-step method is used. for a transformer having a single primary winding, it is usual to connect an auto-transformer with a middle point tap, a reactance or a resi stance between the taps to prevent. themcurrence of high currents during the transition period. Such switches have been constructed in which the several. brushes. are moved simultaneously over the contacts with the one brush in advance of the other. But this arrangement requires a large amount of space and is uneconomical in construction.

It is, therefore, among the objects of the present invention to provide a switch in which the switching action takes place in a step-by-step manner while the electric circuit is maintained during the entire switching operation.

1 further object of the invention is to provide a switch in which the contact arms will not move simultaneously over the contact members but in which one arm will move in ad ance of the other.

Another object of the invention is to provide a switch having a step-by-step movement in which the contact members are of substantially the same width as the brush members thereby permitting the insertion of a greater number of contacts in the same space than was possible heretofore.

Objects and advantages, other than those above set forth, will be ap arent from the following description of t e drawings in which Figure 1 is a partial vertical cross-sectional view of one embodiment of the invention,

Fig. 2 is a partial top plan view of Fig. 1, and

Fig. 3 is a schematic diagram illustrating 261,930, and in Germany May 25, 1928.

the manner in which the switch is to be connected.

Referring more particularly to the drawings by characters of reference, the numeral 6 indicates a base plate of insulating material secured to a piece of electrical apparatus (not shown). A hollow cylindrical support 7 is attachedto the base plate 6 in an upright position at the center of a circle formed by a plurality of contact members 8. Support 7 is formed. with an annular portion 9 extending therefrom, the purpose of which Will appear hereinafter, and is adapted to receive a spindle. 12 which is arranged to be rotated by a handle 13 secured thereto by means of a tube 15 of suitable insulating material. An arm lti is attached, at one ofits ends, to spindle 12. to rotate therewith and is attached at the other end to a spindle 17 to secure rotation thereof for operating the switch as will be apparent. An annular cam member 10 having aplurality of serrations 11, about the circumf'erence, is also attached to the base plate 6. v

A main contact arm 18 having brushes 20 and 21 at the ends thereof is arranged to rotate on spindle 17 whereby brush 2O slides on the upper side of the contact members 8 and brush 21 slides on the upper side of extension 9 of support 7. An are shaped rack 22 is secured tothe underside of arm 18 to provide a means for moving the same as will appear hereinafter. A second or auxiliary contact arm 23 is arranged in rotatable insulated relation on spindle 17 and is provided with an arc shaped rack 25, for cooperation with members to be hereinafter described, and is equipped at one end with a brush 26 sliding on the underside of contact members 8 and is provided at the other end with a brush 27 sliding on cam 10.

Contact arm 23 is formed with extensions 30 and 31, at an angle to the longitudinal axis thereof, provided at their ends with rollers 32 and 33" adapted to move into and out of the serrations of cam 10 as'will be described. A gear 35 formed of suitable insulating material is mounted on a spindle 36 fixed to spindle 17' and rotates in contact with racks 2.? and 25.

The operation of the switch will now be described. When the handle 13 forms a portion of a straight line determined by a contact 8, spindle 17 and spindle 12, both brushes 20 and 26 are on the same contact 8. Movement of handle 18 in a clock-wise direction into the position shown in Fig. 2 causes similar rotation of spindle 12 and arm 16. Arm 16 moves spindle 17 into the position shown without rotation of the spindle 17. Rollers 32 am 33, being connected with spindle 17 through contact arm 28 are forced to move over the s rrations 11 of the fixed cam 10. CDDtP-Ct arm 23 is, therefore, moved in a clock-wise direction so that brush 26 moves ahead to the next contact 8. Movement of arm 23 and its associated rack in one or clock-wise direction causes rotation of gear 353 which tends to move rack 22 and contact arm in the opposite or counter clock-wise direction. But the clock-wise movement of spindle 17 is exactly suiiicient to balance or neutralize the tendency to counter clock-wise moren'ient of the contact arm 18 so that brush 2.) remains on the same contact 8 as was the case when movement of handle 13 was started.

The several portions of the device are now in the position shown in the drawings. Furclock-wise movement of handle 13 causes in of the above described movement with respect to spindle 12. arm 16 and spindle 1? so that the substantially continuous movement of spindle 17 and the rollers 32 and 33 es contact arm 23 a counter clockwise idency which is exactly neutralized by the opposing movement of rack 25 and gear 35, so th t brush 16 remains on the contact 8 to which it has been advanced as shown. The counter clock-wise movement is, however, transmitt d through gear 35 and rack 22 in the opposite direction, thereby advancing brush 20 to the contact on which brush 26 rests as a result of the movement described above. It will thus be apparent that the present invention superimposes a scissorsiike movement of the arms 18 and 23 on the continuous line movement of spindle 17 thereby producing a step-by-step action of the contact arms so that the main contact 18 remains in the former position until contact has been established by the auxiliary contact arm The invention claimed is:

1. In a switch for changing the tap connections of a transformer under load, a lurality of tap contacts, a plurality of brus 16S, and means for alternately and intermittently moving said brushes in sequence over the taps and simultaneously moving said brushes relative to each other.

2. In a switch for changing the tap connections of a transformer under load, a plurality of tap contacts, a plurality of brushes arranged for super-imposed movement over said contacts, means interconnecting said brushes to create a tendency for movement thereof in opposite directions, and means for alternately causing intermittent movement of said brushes in the same direction.

3. In a switch for changing the tap connections of a transformer under load, a. plurality of tap contacts, a plurality of brushes arranged for super-imposed movement over said contacts, racks secured to each of said brushes, :1 gear engaging said racks to create a tendency for movement of said brushes in opposite directions, and means for alternate- 1y causing intermittent movement of said brushes in the same direction.

4. In a switch for changing the tap connections of a transformer under load, a plurality of tap contacts, a plurality of brushes arranged for super-imposed movement over said contacts, means interconnecting said brushes to create a tendency for movement thereof in opposite directions, a substantially circular cam member arranged in fixed relations to said contacts, and means connected with one of said brush members and engaging said cam for causing intermittent movement of said brushes in the same direction.

5. In a switch for changing the tap con nections of a transformer under load, a plurality of tap contacts, a plurality of brushes arranged for super-imposed movement over said contacts, racks secured to each of said brushes, a gear engaging said racks to create a tendency for movement of said brushes in opposite directions, a substantially circular cam arranged in fixed relation to said contacts, and means connected with one of said brush members and engaging said cam for causing intermittent movement of said brushes in the same direction.

In testimony whereof we have hereunto subscribed our names this 27th day of April, A. D. 1929.

ARNOLD HALLER. SIGURD RUMP. 

